Approach
Diagnosis is made by a comprehensive clinical history from reliable sources, most often parents. The approach to diagnosis is similar to the evaluation of other neurodevelopmental disorders, and begins with a thorough, detailed history focusing on onset, time course, phenomenology such as urges or sensations associated with tics, exacerbating and ameliorating factors, family history, and presence of comorbid symptoms. A general medical and neurological examination is indicated. Phenomenology of the tics is a key component, with emphasis on differentiating from stereotypies, compulsions, and chorea. Currently there is no identifiable biological marker for a TS diagnosis.
History
Inquiry regarding onset of tics is important, as they typically begin in early childhood, characteristically with eye blinking or other facial tic.[2] Often the tics worsen in late childhood prior to puberty.[3] Although most often the tics tend to wax and wane, with one tic replacing another, sometimes tics can present abruptly or in acute bursts.
Potential day-to-day exacerbating factors, such as medications (stimulants in some patients, including caffeine and over-the-counter decongestants or cold remedies), fatigue, boredom, and stressors should be noted.[52] Over time, changes in hormonal levels during the menstrual cycle and puberty can also affect their course.[53] Tics have been shown to persist in various stages of sleep.[54]
It is important to define the characteristics and types of tics for accurate diagnosis and monitoring. Differentiation of tic disorders from other common childhood-onset medical disorders is important. For example, coughing, sniffing, blinking, and nose-twitching should be differentiated from allergies or asthma.[55] Children with TS are frequently initially evaluated and treated by allergists and ophthalmologists before the correct diagnosis is made.
Simple tics:
Motor tics are the classic, brief movements, such as grimacing, blinking, head jerking, shoulder shrugging, or nose twitching. Briefly sustained postures (e.g., blepharospasm, oculogyric movements, and sustained mouth opening) can also be classified as simple motor tics.
Vocal tics may include coughing, sniffing, throat clearing, grunting, squeaking, and screaming.
Complex tics:
Motor tics are longer-acting, more purposeful or orchestrated patterns of movement, such as echopraxia (imitating gestures) and copropraxia (obscene gestures).
Vocal tics are longer, more orchestrated patterns of speech, such as coprolalia (uttering obscenities or profanities) and echolalia (repeating another person's last syllable, word, or phrase).[1] Although coprolalia can cause considerable social distress, it occurs in only approximately 10% of patients.[56]
At times it may be difficult to differentiate complex motor tics from compulsions (which require a cognitive component), as obsessive-compulsive symptoms frequently co-occur in children with TS. It is particularly important to evaluate onset of OCD symptoms; there is a subgroup of patients with OCD with abrupt, explosive, and/or dramatic onset over 24 to 48 hours that may be aetiologically linked to infectious or autoimmune aetiologies.[57][58][59]
A distinguishing characteristic of motor and vocal tics is the sensation that precedes the movement or sound, often termed premonitory sensations or 'urges'. Sometimes patients can localise these feelings to particular parts of the body, such as the body part from which the tic emerges, described as a 'burning or build-up of tension'. Most patients experience an intensification of these sensations or urges when they suppress their movements.
Patients also often describe another associated experience, often of a compulsive nature, in which the tic must be repeated until it feels 'just right'. After performing the tic, a sense of relief is experienced, although sometimes brief. Descriptions of these sensations may be difficult for younger patients to express, but there is a quantitative, pictorial rating scale of these urges and sensations that can be used with children.[60]
Inquiry regarding the patient's behaviour and performance both at school and at home is essential. Problems with learning or classroom behaviour may indicate the presence of ADHD or OCD. Systematic review of ritualistic behaviour or compulsive habits, mood disorder symptoms, and non-OCD anxiety such as phobias or separation anxiety should also take place. Specific inquiry regarding a family history of tics, Tourette's disorder, and/or OCD is essential, and general inquiry as to affective disorders, ADHD, or learning or substance abuse problems is helpful.
Examination
Often during the initial examination, the patient’s tics may not be observed, as he or she may inadvertently or unconsciously suppress the symptoms. The patient should be asked to relax and allow the tics to emerge or 'come out' naturally. On the other hand, some patients' tics may be more pronounced than usual during the initial visit as a result of the patient's anxiety. Tics will usually be more prominent or typical after the first visit, but do not need to be present during the initial examination to make a diagnosis. Brief, repetitive, stereotyped movements that may be incorporated into normal gestures should be noted. Asking the patient to suppress his or her tics for 30 to 60 seconds can induce premonitory sensations, which can aid in diagnosis.
Any compulsive behaviours, such as touching, tapping, or drumming, should be noted. Briefly noting if the patient's parents and/or siblings exhibit tics or compulsive habits can also be helpful.
In general, most patients with TS have a normal neurological examination, including cranial nerves, muscle strength, sensory modalities, coordination, gait, and mental status. Typically no further ancillary tests are required if the remainder of the patient's examination is normal. If a neurological deficit is found suggesting a possible upper motor-neuron lesion, an MRI of the brain can be obtained. If there is evidence of possible seizure activity in the patient's history or examination, an EEG should be performed.
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